Radiopaque marker system and method of use

ABSTRACT

A temporary and retrievable radiopaque marker and discrete radiopaque marker for use on an implantable endoprosthesis. The elongate marker has a proximal end, a distal end, and a thickness. At least a portion of the marker is radiopaque and the marker is removably-attached to the implantable endoprosthesis.

This application is a continuation of U.S. application Ser. No.08/905,821 filed on Aug. 1, 1997.

BACKGROUND OF THE INVENTION

This invention relates generally to a retrievable radiopaque marker or adiscrete radiopaque marker for use on an implantable endoprosthesis suchas a stent.

Implantable endoprostheses including stents, stent-grafts, and graftsare used in percutaneous transluminal coronary angioplasty and in othermedical procedures to repair and support diseased or damaged arteriesand body lumens. Grafts are implanted to cover or bridge leaks ordissections in vessels. Stent-grafts are stents which generally have aporous coating attachment and may be implanted by percutaneoustransluminal angioplasty. Unsupported grafts are porous tubes which aretypically implanted by surgical cut-down.

In order to visualize the passage and placement of the implantableendoprosthesis in arteries and body lumens, many surgical procedures areperformed under fluoroscopy. The surgical delivery device andimplantable endoprosthesis may be visualized if they are radiopaque andoffer radiographic contrast relative to the body. For example, X-rayradiation may be used to visualize surgical delivery devices anddeployment of the implant in the body. Also, radiographic contrastsolution may be injected into the body lumen so that the lumen may beseen in the fluoroscopic image.

In order for an implantable endoprosthesis to be radiopaque, it must bemade from a material possessing radiographic density higher than asurrounding host tissue and have sufficient thickness to affect thetransmission of x-rays to produce contrast in the image. Reference ismade to the clad composite stent shown in U.S. Pat. No. 5,630,840. Animplantable endoprosthesis may be made of metals including tantalum orplatinum having relatively high radiographic densities. Other metalssuch as stainless steel, superalloys, nitinol, and titanium having lowerradiographic densities may also be used. Reference is made toimplantable devices shown in U.S. Pat. Nos. 4,655,771; 4,954,126; and5,061,275.

An implantable polymeric endoprosthesis is generally radiolucent anddoes not possess sufficient radiographic density to be easily imaged byfluoroscopy. To improve the imaging of polymeric materials, polymers maybe mixed with radiopaque filler materials prior to molding or extrudingin order to enhance the radiographic density. However, a disadvantage ofusing fillers with polymers is that changes in the properties of thepolymer may occur. For example, the addition of fillers may reduce thestrength or ductility of the polymer.

There is a need for an improved radiopaque marker for use in medicaldevices, particularly in temporary medical devices having lowradiopacity. The need to improve the radiopacity of a relatively lowradiopaque implantable endoprosthesis or improve imaging in lowradiopaque conditions is particularly important for surgery,micro-surgery, neuro-surgery, and conventional angioplasty proceduresperformed under fluoroscopy. Physicians are constantly being challengedto place small implants at remote intraluminal locations.

Various devices having radiopaque markers are shown in U.S. Pat. Nos.4,447,239; 5,423,849; and 5,354,257.

All documents cited herein, including the foregoing, are incorporatedherein by reference in their entireties for all purposes.

SUMMARY OF THE INVENTION

Accordingly, there is a need for retrievable radiopaque markers for usein implantable endoprostheses to improve radiopacity and thelocatability of endoprostheses in various medical procedures. Providingtemporary radiopacity is especially advantageous for implantableendoprostheses having little or no radiopacity. The markers allowradiographic identification of one or more locations of interest on animplantable endoprosthesis. The locations of interest may include one ormore covered or coated regions.

Alternative embodiments include threading the markers adjacent a helicalstrand in the implantable endoprosthesis, circumferentially around theimplantable endoprosthesis, in a straight line in the axial direction ofthe implantable endoprosthesis, or disposing the wire in the form ofpigtail-shaped rings, coils, or knots around filament crossing points inthe implantable endoprosthesis.

Temporary retrievable radiopaque markers in the fabric or coveringmaterials of an implantable endoprosthesis are advantageous forindicating the location of the fabric or covering during implantation.After implantation, the temporary retrievable radiopaque marker may beretrieved so as not to effect the function of the endoprosthesis.

A disadvantage of some permanent radiopaque markers is that they maycompromise structural integrity, may not be biocompatible or biostable,and may be more thrombogenic than the implantable endoprosthesis.

The temporary retrievable radiopaque marker of the present inventionadvantageously allows most any implantable endoprosthesis to havetemporary radiopacity over a predetermined portion of its structure, andassists with proper positioning and locatability of the implantableendoprosthesis in a body lumen.

Use of temporary retrievable radiopaque markers on an implantableendoprosthesis is advantageous because the radiopaque property may bepresent only for a desired time period. Generally, radiopacity is mostdesirable during placement of the implant. Once the implantableendoprosthesis is implanted, it may be more desirable to image thedevice with techniques such as ultrasound, magnetic resonance, andendoscopy and avoid further radiation exposure to the patient. Temporaryradiopacity may be made by incorporating non-integral, retrievableradiopaque constituents into the implant Thus, light metals, thinradiopaque metals, polymers, and ceramics may be utilized for a widerange of properties and flexibility in design of the endoprosthesis:

Attenuation is the change in the number of photons in the incident x-raybeam due to the interaction with an absorber. To image an objectimplanted in the body, it would be desirable to have the objectattenuate x-rays more than body tissue, bone, and fat so that thedifference in contrast will be obvious in a radiograph. The difficultyin selecting a radiopaque material for surgical implants is that thematerial must have desirable radiographic characteristics andbiocompatibility.

In order to make an implant more radiopaque, a substance which absorbsmore x-rays can be deposited on or mixed in with the implant material.If the implant absorbs more x-rays than the surrounding medium (forexample tissue in the body), it will be visible as a sharp change incontrast on an x-ray film or fluoroscopy image.

The fraction of x-ray energy transmitted through the absorber isquantitatively predicted by the following equation described in ThePhysics of Radiology, Fourth Ed., H. Johns, J. Cunningham, 1983, pp.137-142.

N=N₀e^(-μx)

N=number of photons transmitted through x

N₀=number of photons in the incident beam

μ=linear attenuation coefficient of the absorber

x=absorber thickness

N/N₀ would be the fraction of incident x-ray energy that is transmittedthrough the absorber. A more radiopaque material would have a lesserfraction of transmitted energy than a more radiolucent material.Therefore, to enhance the radiopacity of a material, such as the markermaterial, it would be desirable to select a material with high x-rayabsorbing capability to minimize the fraction of transmitted energy.This radiopacity capability is proportional to the linear attenuationcoefficient and the thickness of the absorber material. The higher theattenuation coefficient of the absorber material for a given thickness,the more radiopaque the absorber will be. The attenuation produced by anabsorber is dependent upon the number of electrons and atoms present inthe absorber. One way of quantifying this absorption characteristic iswith the atomic attenuation coefficient which is directly proportionalto the linear attenuation coefficient and the atomic number of theabsorber element. Radiopacity is therefore generally proportional to theatomic number (number of electrons in the atom) of the material.Candidate materials for enhancing the radiopacity of surgical implantswould have higher atomic numbers than the elements present in the bodyand would have to be biocompatible. The atomic number must besufficiently high so that relatively small thickness of absorbermaterial can be used in the body. Reference is also made to linearattenuation coefficient described in U.S. Pat. No. 5,628,787. Referenceis made to Table 1 which describes a number of elements and theirrespective atomic numbers and certain linear attenuation coefficients.

Element Atomic Number or Linear Attenuation or Material Effective AtomicNumber Coefficient at 50 KeV, cm⁻¹ hydrogen 1 .000028 carbon 6 .417 fat6.46 .193 water 7.51 .2245 muscle 7.64 .233 air 7.78 .000247 nitrogen 7.000228 oxygen 8 .000280 bone 12.31 .573 titanium 22 5.46 iron 26 15.42cobalt 27 18.94 bromine 35 13.29 zirconium 40 40.04 iodine 53 60.76barium 56 49.68 tantalum 73 94.95 platinum 78 149.08 gold 79 140.12 lead82 91.17 bismuth 83 82.12 iridium 77 151.53 nickel 28 21.98

The elements hydrogen, oxygen, carbon, and nitrogen are commonly foundin the body and in polymers, so elements with higher atomic numbers thanthese should enhance the radiopacity of a polymer implant or marker.Tantalum, zirconium, titanium, barium, bismuth, and iodine are known tobe non-toxic in certain concentrations and thus are candidate elementsfor enhancing radiopacity of a polymer marker in an implant. Theseelements can be added to the polymer in various loading percentages andthe threshhold above which the loading causes unsatisfactory changes inthe polymer characteristics can be determined through material anddevice testing. The elements which can be added in quantities sufficientto enhance radiopacity and maintain an acceptable level of polymerproperties and which are biocompatible could be utilized in markers. Thebiocompatible elements with a range of atomic numbers from about 22 toabout 83 and having linear attenuation coefficients in the range fromabout 5.46 to about 151.53 cm⁻¹ at 50 KeV should provide enoughenhancement in radiopacity without excessive thickness being necessaryto be useful in markers. These elements would include at least titanium,vanadium, chromium, iron, cobalt, nickel, copper, bromine, zirconium,niobium, molybdenum, silver, iodine, barium, tantalum, tungsten,platinum, gold, and bismuth. The preferred metallic elements forbiocompatibility and radiopacity are titanium, zirconium, tantalum, andplatinum. The preferred organic elements for biocompatibility andradiopacity are bromine, iodine, barium, and bismuth. Especiallypreferred elements are tantalum, platinum, barium, and bismuth becauseof their high atomic numbers and biocompatibility (atomic numbers from56 to 83 and linear attenuation coefficients from about 49.68 to149.08). Tantalum and platinum are used as stent components and bariumsulfate and bismuth trioxide are used as radiopaque enhancements forpolymer catheters.

In sum, the invention relates to an implantable endoprosthesis andradiopaque marker system. The system includes an implantableendoprosthesis adapted to be disposed in a body lumen and at least oneelongate marker. The marker has a proximal end, a distal end, athickness, and at least one radiopaque portion. The radiopaque portionincludes a radiopaque material. The marker is removably attached to atleast a portion of the implantable endoprosthesis and is removeable fromthe endoprosthesis when the endoprosthesis is in vivo. The radiopaquematerial may be at least partially dispersed from the marker over time.The radiopaque material may have a linear attenuation coefficient offrom about 5.46 cm⁻¹ at 50 KeV to about 151.53 cm⁻¹ at 50 KeV. Thethickness of the marker may range from about 20 microns to about 500microns and the radiopaque material may have at least one element withan atomic number of from about 22 to about 83. The marker may include anoxide or salt material having at least one element with an atomic numberof from about 22 to about 83. The marker may include barium sulfate,bismuth trioxide, iodine, iodide, titanium oxide, zirconium oxide, gold,platinum, silver, tantalum, niobium, stainless steel, or combinationsthereof. The marker may be coated or alloyed with a radiopaque materialthat has a linear attenuation coefficient of from about 5.46 cm⁻¹ at 50KeV to about 151.53 cm⁻¹ at 50 KeV. The marker may cross at least oneportion of the implantable endoprosthesis. The marker may be a wire,mono-filament, multi-filament, ribbon, suture, spring, or combinationsthereof. The marker may include metals, polymers, copolymers, ceramics,or combinations thereof. The marker may include at least one hollow,cavity, or porous portion. The marker may include at least one hollow,cavity, or porous portion therein adapted to receive the radiopaquematerial removably attached therein. The proximal end of the marker maybe connected to at least one of the implantable endoprosthesis deliverydevice or a handle. The proximal end of the marker may have a hook,knob, ring, or eyelet attached thereto. The marker system may include adelivery device wherein the implantable endoprosthesis and marker aredisposed in the delivery device and adapted for implantation into a bodylumen. The implantable endoprosthesis may include a stent, stent-graft,graft, filter, occlusive device, or valve. The marker system may includeat least one elongate wire removably attached to the implantableendoprosthesis wherein the marker crosses at least a portion of theimplantable endoprosthesis and crosses the at least one elongate wire.

The invention also relates to an implantable endoprosthesis andradiopaque marker system. The marker system includes an implantableendoprosthesis adapted to be disposed in a body lumen and at least oneelongate marker. The marker is removably attached to the implantableendoprosthesis. The marker has a proximal end, a distal end, athickness, at least one hollow, cavity, or porous portion, and at leastone radiopaque material having a linear attenuation coefficient of fromabout 5.46 cm⁻¹ at 50 KeV to about 151.53 cm⁻¹ at 50 KeV wherein theradiopaque material is removably attached to at least one of the hollow,cavity, or porous portions. The radiopaque portion may include a liquid,solid, powder, gel, wire, mono-filament, multi-filament, pellet,particle, or combinations thereof.

The invention also relates to a method of marking an implantableendoprosthesis including removably-attaching at least one elongatemarker having a proximal and distal end to a portion of an implantableendoprosthesis to form an assembly. The marker includes at least oneradiopaque material having a linear attenuation coefficient of fromabout 5.46 cm⁻¹ at 50 KeV to about 151.53 cm⁻¹ at 50 KeV; disposing theimplantable endoprosthesis and marker assembly in a delivery system;inserting the delivery system in a body lumen; deploying the implantableendoprosthesis and marker assembly from the delivery system into thebody lumen; and removing at least a portion of marker from theimplantable endoprosthesis. The method may further include performingone or more medical procedures using the markers as a surgical guideprior to removing at least a portion of the marker from theendoprosthesis. The marker may include a radiopaque portion and asecondary portion. The radiopaque portion is first substantially removedfrom the implantable endoprosthesis prior to removal of the remainingsecondary portion of the marker. Removing the marker from theimplantable endoprosthesis may be performed by a force controlled fromoutside the body. The method may further include removably-attaching atleast one wire to at least a portion of the implantable endoprosthesisand crossing the wire or the elongate marker over the other such thatone of the marker or the wire requires removal prior to removal of theother from the implantable endoprosthesis.

The invention also relates to an implantable endoprosthesis andradiopaque marker system. The marker system includes an implantableendoprosthesis having a tubular and radially expandable structureadapted to be disposed in a body lumen and at least one elongate marker.The marker is removably attached to the implantable endoprosthesis. Themarker includes a radiopaque material having a linear attenuationcoefficient of from about 5.46 cm⁻¹ at 50 KeV to about 151.53 cm⁻¹ at 50KeV, a proximal end, a distal end, and a thickness. The radiopaquematerial disperses into the body when in vivo. The implantableendoprosthesis may include an axially flexible structure including aplurality of the elongate elements which are interwoven in a braid-likeconfiguration.

The invention also relates to a temporary radiopaque marker. The markerincludes an elongate marker having a proximal end, a distal end, anaverage thickness of from about 20 microns to about 500 microns, andincludes a radiopaque material having a linear attenuation coefficientof from about 5.46 cm⁻¹ at 50 KeV to about 151.53 cm⁻¹ at 50 KeV. Themarker is adapted to be removably attached to an implantableendoprosthesis. The proximal end of the marker may include a hook, knob,or eyelet.

The invention also relates to in combination, a discrete radiopaquemarker and implantable endoprosthesis. The implantable endoprosthesishas one or more attachment areas and is adapted to be disposed in a bodylumen. One or more elongate markers have a proximal end, a distal end,and one or more portions therebetween. The markers have a thickness offrom about 20 microns to about 500 microns and include a radiopaquematerial having a linear attenuation coefficient of from about 5.46 cm⁻¹at 50 KeV to about 151.53 cm⁻¹ at 50 KeV. The one or more portions ofthe marker are deformed and permanently disposed about the one or moreattachment areas of the endoprosthesis. The markers may be deformed byplastic deformation, elastic deformation, or combinations thereof. Themarker may include a twist, knot, crimp, weld, and combinations thereof.The one or more portions may be ductile. The marker may be a spring. Thedeformation of one or more portions of the marker into an attachmentposition on the attachment area thereby prevents the marker fromreleasing from the implantable endoprosthesis.

Still other objects and advantages of the present invention and methodsof construction of the same will become readily apparent to thoseskilled in the art from the following detailed description, wherein onlythe preferred embodiments are shown and described, simply by way ofillustration of the best mode contemplated of carrying out theinvention. As will be realized, the invention is capable of other anddifferent embodiments and methods of construction, and its severaldetails are capable of modification in various obvious respects, allwithout departing from the invention. Accordingly, the drawing anddescription are to be regarded as illustrative in nature, and not asrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an implantable endoprosthesis delivery systemincluding a retrievable radiopaque marker disposed on an implantableendoprosthesis;

FIG. 2 is a side view of the delivery system and a deployed retrievableradiopaque marker and implantable endoprosthesis in a body lumen;

FIG. 3 is a side view of one possible arrangement of a retrievableradiopaque marker being retrieved from a deployed implantableendoprosthesis in a body lumen;

FIGS. 4a, 4 b, and 4 c are cross-sectional views of three alternativemarker dispositions on an implantable endoprosthesis at section 4—4 ofFIG. 2;

FIG. 5 is a side view of a retrievable radiopaque marker disposed on animplantable endoprosthesis;

FIG. 6 is a side view of a retrievable radiopaque marker disposed in ahelical pattern about the perimeter of an implantable endoprosthesis;

FIG. 7 is a side view illustrating one possible arrangement of astraight wire and retrievable radiopaque marker disposed on animplantable endoprosthesis;

FIG. 8 is a side view of a delivery device illustrating one arrangementof a wire and retrievable radiopaque marker;

FIG. 9 is a side view of a relatively flexible retrievable radiopaquemarker;

FIGS. 10a-10 e are cross-sectional views of five alternative radiopaquemarkers at section 10-10 of FIG. 9;

FIGS. 11a-11 c are side views of three alternative radiopaque markers;

FIG. 12 is a side view illustrating one possible arrangement of discreteradiopaque markers disposed on an implantable endoprosthesis;

FIG. 13 is the detail bounded by the dashed-line circle in FIG. 12illustrating a radiopaque marker disposed around one implantableendoprosthesis wire crossing point;

FIG. 14 is a side view illustrating a discrete radiopaque marker; and

FIG. 15 illustrates the discrete radiopaque marker positioned on anembolization occlusion coil intravascular device.

DETAILED DESCRIPTION OF THE INVENTION

Reference is made to FIGS. 1-3 which illustrate a stent delivery device10 in various stages of deployment having one or more retrievableradiopaque markers 14 disposed on an implantable endoprosthesis 16. Theretrievable radiopaque markers 14 are disposed on the endoprosthesis 16preferably before loading into the outer tube of a delivery device 10.Reference is made to a delivery device shown in U.S. Pat. No. 5,026,377.

As shown in FIG. 1, a proximal end 14 a of the retrievable radiopaquemarker 14 may be attached at portion 8 which is on the outside surfaceof the inner tube of a delivery device 10 and an area proximal of theproximal end of the implantable endoprosthesis 16. Other attachmentareas are also possible on the delivery device 10. Attachment of theproximal end 14 a of the retrievable radiopaque marker 14 to thedelivery device may be made by mechanical (e.g., clamp or frictionalcontact on the surface, interweaving to components in the device, ortying), thermal (e.g. metal or polymer welding), or chemical (e.g.,adhesive or gel bond) fastening systems. A predetermined length of theretrievable radiopaque marker 14 may be gathered at or around portion 8to allow the implantable endoprosthesis 16 to deploy from the deliverydevice 10. Alternatively, as illustrated in FIG. 8, the retrievableradiopaque marker 14 may be disposed on the implantable endoprosthesis16, be disposed in a channel or lumen of the delivery device 10, andexit out a port 17 in the hub 19 and be attached to handle 21. Thehandle 21 may be a ring or a similar shape device adapted to be graspedand aid in retrieval and manipulation of the retrievable radiopaquemarker 14 or straight wire 18. Once the implantable endoprosthesis 16 isimplanted, the retrievable radiopaque marker 14 may be removedproximally from the body by a force in the proximal directiontransmitted to the handle 21. Table 2 lists preferred embodiments of theinvention.

TABLE 2 Preferred Marker Preferred Marker Metal Organic RadiopaqueRadiopaque Preferred Marker Marker Type Description Function DevicesAgents Agents Matrix Materials Retrievable, threading on helix markoverall stent braided tubular Ti, Ta, Zr, Pt Br, I, Ba, Bi Polyethylene,Temporary length, location in stents, filters, silicone, stainlessvessel occlusion, valves steel, Elgiloy ® Retrievable, threading aroundmark stent ends, braided tubular Ti, Ta, Zr, Pt Br, I, Ba, BiPolyethylene, Temporary circumference location in vessel, stents,filters, silicone, stainless covering length, occlusion, valves, steel,Elgiloy ® expansion stent grafts Retrievable, threading on mark overallstent braided tubular Ti, Ta, Zr, Pt Br, I, Ba, Bi Polyethylene,Temporary straight axial line length, location in stents, filters,silicone, stainless vessel occlusion, valves, steel, Elgiloy ® stentgrafts Retrievable, spring mark overall stent braided tubular Ti, Ta,Zr, Pt Br, I, Ba, Bi Polyethylene, Temporary length, location in stents,filters, silicone, stainless vessel, expansion occlusion, valves, steel,Elgiloy ® stent grafts Discrete, pigtail rings mark stent ends braidedtubular Ti, Ta, Zr, Pt Br, I, Ba, Bi Polyethylene, Permanent or center,location stents, filters, silicone, stainless in vessel, occlusion,valves, steel, Elgiloy ® expansion stent grafts Discrete, coits markstent ends braided tubular Ti, Ta, Zr, Pt Br, I, Ba, Bi Polyethylene,Permanent or center, location stents, filters, silicone, stainless invessel, occlusion, valves, steel, Elgiloy ® expansion stent graftsDiscrete, knots mark stent ends braided tubular Ti, Ta, Zr, Pt Br, I,Ba, Bi Polyethylene, Permanent or center, location stents, filters,silicone, stainless in vessel, occlusion, valves, steel, Elgiloy ®expansion stent grafts

For description purposes, the markers of the invention can be segregatedinto types; retrievable temporary and discrete permanent markers. Aretrievable temporary marker is generally a strand or strands ofmaterial having radiopacity which is loosely or removably incorporatedwithin the implantable device and which can be removed from the devicesometime after implantation by pulling on a free end of the marker or byhaving the marker extend beyond the device to an attachment point on thedelivery system or extend through the delivery system and out of thebody where it can be grabbed and pulled free of the implant. A discretepermanent marker is generally a strand of material having radiopacitywhich is securely attached to the implantable device and does notsignificantly extend away from the device.

An example of a retrievable temporary marker is a radiopaque strand ofmaterial loosely passed through or threaded into a braided tubular stentwith an end of marker extending away from the stent and attached to theinner tube of the coaxial tube delivery system. As the stent is deployedfrom the delivery system the marker is used to locate the position ofthe stent with regard to the stricture. After stent deployment, thedelivery system is normally pulled out of the body along the guidewire.The radiopaque marker would be pulled free of the stent as the deliverysystem is retrieved.

An example of a discrete permanent marker is a coil, knot, or ring oftantalum wire around a feature of a stent, such as a stent wire crossingpoint. The tantalum wire is wrapped, coiled, or tied around the stentwire and thereby is permanently mechanically attached to the device. Thetantalum wire ends are clipped off such that the marker is present as asmall, tight ring around a feature of the stent. The stent with theattached markers is loaded and deployed from the delivery system and themarkers are not retrieved when the delivery system is removed.

The function of the retrievable radiopaque marker is to temporarilyindicate on a radiographic image the location of the stent within thetreatment site and the length of the expanded stent can be determined bymeasuring the length of the marker as it follows the stent shape if themarker was threaded along a stent wire helix or axially along a line inthe stent The marker can be threaded circumferentially at each end ofthe stent covering in a covered stent or stent-graft to indicate thelocation of the radiolucent covering material. The stent expansionduring deployment can be observed radiographically by watching theradiopaque marker helical or circumferential strand open up as theself-expanding stent is released from its radially constrained state.

Discrete markers have the same functional purpose as the retrievablemarkers, but they can be more easily used to mark the specific locationsof features of interest on the stent For example, a discrete marker canbe added to the center of the stent length to aid the physician incentering the stent within the stricture. Discrete markers could be usedto attach covering fabrics or films to stents to make stent grafts sothat the location of the covering on the stent could be determinedradiographically.

The retrievable and discrete markers can be made from biocompatiblemetal wires containing elements with relatively high atomic numbers suchas titanium, tantalum, zirconium, and platinum. The radiopaque elementscan be added by metallurgically alloying or by making clad compositestructures. Another type of marker would be to combine titanium,tantalum, zirconium, or platinum metal or oxide powder with a polymermatrix. Polyethylene or silicone are examples of biocompatible polymersthat could be used as a matrix material. Combination could be performedby compounding with the polymer resin or coating. Organic radiopaquepowders containing elements or salts or oxides of elements such asbromine, iodine, iodide, barium, and bismuth could be used instead ofmetal powders.

EXAMPLE 1

A retrievable, temporary radiopaque marker can be in the form of astrand of metal or polymer containing radiopaque elements, oxides, orsalts of elements with atomic numbers in the range of from about 22 toabout 83 loosely threaded along a helical, circumferential, or axialorientation in an endoprosthesis such as a stent, stent-graft, graft,filter, occlusive device, and valve with a free end of the markerextending out from the endoprosthesis such that it is attached to thedelivery system or passed outside of the body and the marker and isseparated from the implanted endoprosthesis by pulling it free and outof the body. The radiopaque material has a linear attenuationcoefficient of from about 5.46 cm⁻¹ at 50 KeV to about 151.53 cm⁻¹ at 50KeV.

EXAMPLE 2

A retrievable, temporary radiopaque marker can be in the form of astrand of metal or polymer containing radiopaque elements, oxides, orsalts of elements with atomic numbers in the range of from about 22 toabout 83 formed into a spring and disposed within an endoprosthesis suchas a stent, stent-graft, graft, filter, occlusive device, and valve witha free end of the marker extending out from the endoprosthesis such thatit is attached to the delivery system or passed outside of the body andthe marker and is separated from the implanted endoprosthesis by pullingit free and out of the body. The radiopaque material has a linearattenuation coefficient of from about 5.46 cm⁻¹ at 50 KeV to about151.53 cm⁻¹ at 50 KeV.

EXAMPLE 3

A retrievable, temporary radiopaque marker can be in the form of astrand of ductile metal wire, ribbon, or braided wire containingradiopaque metallic elements with atomic numbers in the range of fromabout 22 to about 83, preferably titanium, tantalum, zirconium, andplatinum disposed within an endoprosthesis such as a stent, stent-graft,graft, filter, occlusive device, and valve with a free end of the markerextending out from the endoprosthesis such that it is attached to thedelivery system or passed outside of the body and the marker and isseparated from the implanted endoprosthesis by pulling it free and outof the body. The radiopaque material has a linear attenuationcoefficient of from about 5.46 cm⁻¹ at 50 KeV to about 149.08 cm⁻¹ at 50KeV.

EXAMPLE 4

A retrievable, temporary radiopaque marker can be in the form of astrand of ductile metal wire, ribbon, or braided wire containingradiopaque metallic elements with atomic numbers in the range of fromabout 22 to about 83, preferably titanium, tantalum, zirconium, andplatinum coated or clad composite stainless steel or Elgiloy® wiredisposed on an endoprosthesis such as a stent, stent-graft, graft,filter, occlusive device, and valve with a free end of the markerextending out from the endoprosthesis such that it is attached to thedelivery system or passed outside of the body and the marker isseparated from the implanted endoprosthesis by pulling it free and outof the body. The radiopaque material has a linear attenuationcoefficient of from about 5.46 cm⁻¹ at 50 KeV to about 149.08 cm⁻¹ at 50KeV.

EXAMPLE 5

A retrievable, temporary radiopaque marker can be in the form of astrand of ductile polyethylene or silicone polymer monofilament, ribbon,or multifilament wire containing radiopaque metallic elements withatomic numbers in the range of from about 22 to about 83, preferablycompounded or coated with titanium, tantalum, zirconium, and platinummetal powders or bromine, iodine, iodide, barium, and bismuth element,oxides or salts disposed within an endoprosthesis such as a stent,stent-graft, graft, filter, occlusive device, and valve with a free endof the marker extending out from the endoprosthesis such that it isattached to the delivery system or passed outside of the body and themarker and is separated from the implanted endoprosthesis by pulling itfree and out of the body. The radiopaque material has a linearattenuation coefficient of from about 5.46 cm⁻¹ at 50 KeV to about149.08 cm⁻¹ at 50 KeV.

EXAMPLE 6

A retrievable, temporary radiopaque marker can be in the form of aductile polymer or metal matrix composite wire containing radiopaquemetallic elements with atomic numbers in the range of from about 22 toabout 83, preferably titanium, tantalum, zirconium, and platinum metalpowders or bromine, iodine, iodide, barium, and bismuth element, oxidesor salt powders disposed within an endoprosthesis such as a stent,stent-graft, graft, filter, occlusive device, and valve with a free endof the marker extending out from the endoprosthesis such that it isattached to the delivery system or passed outside of the body and themarker and is separated from the implanted endoprosthesis by pulling itfree and out of the body. The radiopaque material has a linearattenuation coefficient of from about 5.46 cm⁻¹ at 50 KeV to about149.08 cm⁻¹ at 50 KeV.

EXAMPLE 7

A discrete, permanent radiopaque marker can be in the form of a ductilemetal wire, ribbon, or braided wire containing radiopaque metallicelements with atomic numbers in the range of from about 22 to about 83,preferably titanium, tantalum, zirconium, and platinum attached bywrapping, coiling, or tying around features within an endoprosthesissuch as a stent, stent-graft, graft, filter, occlusive device, and valvesuch that the marker stays permanently attached by mechanical oradhesive forces to the endoprosthesis during deployment from thedelivery system for the life of the implant. The radiopaque material hasa linear attenuation coefficient of from about 5.46 cm⁻¹ at 50 KeV toabout 149.08 cm⁻¹ at 50 KeV.

EXAMPLE 8

A discrete, permanent radiopaque marker can be in the form of a strandof ductile metal wire, ribbon, or braided wire containing radiopaquemetallic elements with atomic numbers in the range of from about 22 toabout 83, preferably titanium, tantalum, zirconium, and platinum coatedor clad composite stainless steel or Elgiloy® wire ductile metal wire,ribbon, or braided wire containing radiopaque metallic elements withatomic numbers in the range of from about 22 to about 83, preferablytitanium, tantalum, zirconium, and platinum attached by wrapping,coiling, or tying around features within an endoprosthesis such as astent, stent-graft, graft, filter, occlusive device, and valve such thatthe marker stays permanently attached by mechanical or adhesive forcesto the endoprosthesis during deployment from the delivery system for thelife of the implant. The radiopaque material has a linear attenuationcoefficient of from about 5.46 cm⁻¹ at 50 KeV to about 149.08 cm⁻¹ at 50KeV.

EXAMPLE 9

A discrete, permanent radiopaque marker can be in the form of a strandof ductile polyethylene or silicone polymer monofilament, ribbon, ormultifilament wire containing radiopaque metallic elements with atomicnumbers in the range of from about 22 to about 83, preferably compoundedor coated with titanium, tantalum, zirconium, and platinum metal powdersor bromine, iodine, iodide, barium, and bismuth element, oxides or saltsattached by wrapping, coiling, or tying around features within anendoprosthesis such as a stent, stent-graft, graft, filter, occlusivedevice, and valve such that the marker stays permanently attached bymechanical or adhesive forces to the endoprosthesis during deploymentfrom the delivery system for the life of the implant. The radiopaquematerial has a linear attenuation coefficient of from about 5.46 cm⁻¹ at50 KeV to about 149.08 cm⁻¹ at 50 KeV.

FIGS. 2-3 illustrate an implantable endoprosthesis 16 in a body lumen12. Implantable endoprostheses known in the art include stents,stent-grafts, grafts, filters, occlusive devices, and valves, all ofwhich may incorporate the retrievable radiopaque marker 14 or discretemarker.

FIGS. 4a-4 c illustrate three alternative locations on an implantableendoprosthesis 16 for disposing the retrievable radiopaque marker 14.The retrievable radiopaque marker 14 may be an elongate elementincluding a thread, filament, or ribbon such as a highly radiopaque wirerelatively loosely woven into or wrapped around the inside, outside, orends of the implantable endoprosthesis 16.

Reference is made to FIGS. 5-6 illustrating the retrievable radiopaquemarker 14 disposed in two alternative patterns on the implantableendoprosthesis 16. FIG. 5 shows the marker 14 interwoven or interbraidedloosely along the longitudinal axis of the endoprosthesis 16. FIG. 6shows the marker 14 disposed in a helical pattern about the implantableendoprosthesis 16. Other patterns and dispositions of the marker 14 onthe endoprosthesis 16 are also possible. One or more markers 14 may betemporarily disposed on the implantable endoprosthesis 16 in alternativepatterns to advantageously provide temporary radiopacity topredetermined locations on the implantable endoprosthesis 16.

The retrievable radiopaque marker 14 may be applied temporarily to oneor more surfaces of the implantable endoprosthesis 16 with a relativelyweak bioabsorbable adhesive or gelatin, for instance, as shown in FIGS.4a and 4 c. Alternatively, the retrievable radiopaque marker 14 may beformed into a spring having spring force characteristics and be appliedon the inside surface of the implantable endoprosthesis 16 as shown inFIG. 4c. Spring force allows the retrievable radiopaque marker 14 topress against the interior of the implantable endoprosthesis 16 andprovide temporary radiopacity thereto.

The retrievable radiopaque marker 14 may be braided to form a rope orcable. The retrievable radiopaque marker 14 may be woven orinter-braided into the implantable endoprosthesis 16 during manufacture.

As the implantable endoprosthesis 16 is deployed from the deliverydevice 10, the retrievable radiopaque marker 14 may adjust withexpansion of the implantable endoprosthesis 16 and therebyadvantageously provides radiopacity and viewing of the implantableendoprosthesis 16 position or size during fluoroscopy. Once theimplantable endoprosthesis 16 is fully deployed, the delivery device 10and the retrievable radiopaque marker 14 may be removed from the body.For example, one end of the retrievable radiopaque marker 14 may beattached to the delivery device 10 and the other end may be disposed atpredetermined locations on the implantable endoprosthesis 16. As thedelivery device 10 is withdrawn, the retrievable radiopaque marker 14may be pulled away from implantable endoprosthesis 16 and removed fromthe body. The retrievable radiopaque marker 14 may be looselyincorporated into the implantable endoprosthesis 16 and be easilyretrieved without disturbing the implantable endoprosthesis 16 or bodytissue. Alternatively, the retrievable radiopaque marker 14 may remainon the implantable endoprosthesis 16 for a period of time if there is aneed for follow-up angiography, and then be ultimately removed.

Reference is made to FIGS. 7-8 illustrating an alternative embodimentincluding a retrievable radiopaque marker 14 and wire 18. The wire 18 isused to prevent removal of the marker 14 without first removal of thewire 18. The retrievable radiopaque marker 14 is relatively looselywoven or inter-braided in and out of the implantable endoprosthesis 16,and is maintained in place by another relatively straight, flexible andadjacent movable wire 18. The marker 14 and wire 18 may be made byvarious methods and materials including polymers, metals, ceramics, orsimilar materials.

The wire 18 may be placed inside, outside, or penetrate betweenfilaments of the implantable endoprosthesis 16. The wire 18 andretrievable radiopaque marker 14 are disposed at desired predeterminedareas and in various patterns on the implantable endoprosthesis 16.Various combinations of the wire 18 and retrievable radiopaque marker 14are possible including multiple markers 14 or wires 18. As illustratedin FIG. 8, the retrievable radiopaque marker 14 and wire 18 may bedisposed on the implantable endoprosthesis 16, be disposed in a channelor lumen of the delivery device 10, and exit out a port 17 in the hub 19and be attached to handle 21. The handle 21 may be a ring or a similarshape device adapted to be grasped and aid in retrieval and manipulationof the retrievable radiopaque marker 14. Once the implantableendoprosthesis 16 is implanted, the wire 18 may be removed proximally bya force which liberates the retrievable radiopaque marker 14 and allowsremoval thereof.

A limited amount of interweaving or interbraiding of the retrievableradiopaque marker 14 or wire 18 is generally desired in order tominimize the force required for retrieval. The retrievable radiopaquemarker 14 or wire 18 may be coated with a biocompatible material havinga low coefficient of friction for ease of removal from the implantableendoprosthesis 16.

Reference is made to FIG. 9 illustrating a retrievable radiopaque marker14 preferably made from a relatively flexible wire, suture, filament,ribbon, braided wires, or combinations thereof including radiopaquematerial such as a metal, metallic alloy, or polymer containing amaterial that is highly radiopaque.

FIGS. 10a-10 e illustrate alternative cross-sectional embodiments of theretrievable radiopaque marker 14 taken through the line 10—10 of FIG. 9.FIG. 10a shows a substantially solid member; FIG. 10b shows a hollowmember; FIG. 10c shows a member having pores extending radially into themember; FIG. 10d shows a rectangular or ribbon member; and FIG. 10eshows a braided hollow member. FIG. 10e may also be a substantiallysolid braided member.

A composite radiopaque marker 14 may be made from materials coated orcompounded with a radiopaque substance such as iodine, zirconium oxide,barium sulfate, bismuth trioxide, or a related oxide or salt substance.Composite radiopaque materials may be a radiopaque material containingat least one element having an atomic number, preferably higher thanabout 22. Another radiopaque marker 14 may include gold, platinum,metal, tantalum, metallic alloy, or a polymer containing a radiopaquefiller such as barium sulfate, bismuth trioxide, iodine, iodide, or likematerials.

Reference is made to FIGS. 11a-11 c illustrating alternative embodimentsof a portion of the retrievable radiopaque marker 14. The retrievableradiopaque marker 14 may have at least one hollow portion 15 whichextends throughout the marker 14 for temporary or permanent containmentof a retrievable radiopaque material. For example, a radiopaque core 13as shown in FIG. 11c may be disposed in and retrieved from a hollowportion 15 in the retrievable radiopaque marker 14. One end of theradiopaque core 13 may be attached to the delivery device 10 by a wireor the like and removed from the retrievable radiopaque marker 14 andbody lumen by a force originating from outside the body. The outsidecase of the marker 14 may remain disposed on the implantableendoprosthesis 16 or be removed therefrom. The temporary radiopaque core13 may be solid or include a casing surrounding a solid, gel, powder, orcombination thereof and be held in place with a relatively weakbioabsorbable adhesive gelatin, friction, or by other mechanical orchemical means known in the art in a hollow 15, cavity, or porousportion. The temporary radiopaque core 13 preferably is made of aradiopaque material that has a linear attenuation coefficient of fromabout 5.46 cm⁻¹ at 50 KeV to about 151.53 cm⁻¹ at 50 KeV and is adaptedto be removably attachable in at least one hollow 15, cavity, or porousportion in the marker 14. Alternatively, the core 13 may remain in thehollow 15, cavity, or porous portion of the marker 14 and be removedwhen the marker 14 is retrieved from the body. In alternativeembodiments, one or more closed cavities within the marker 14 or poreson the surface as shown in FIG. 10c or pores extending through to ahollow or cavity portion within the marker 14 (not shown) may beutilized for temporary or permanent containment of a retrievableradiopaque materials or be utilized for a passageway for dispersal ofthe radiopaque materials contained in the marker 14 into the body.

FIG. 12 illustrates discrete radiopaque markers 24 made by forming smallrings or coils of radiopaque wire around features of the implantableendoprosthesis 16. Relatively small and discrete wire loop (pigtail)radiopaque markers 24 are shown at the wire crossing points on thetubular braid.

FIG. 13 illustrates the detail bounded by the dashed-line circle in FIG.12 showing a radiopaque wire loop marker 24 around one implantableendoprosthesis 16 wire crossing point.

FIG. 14 illustrates the marker 24 of FIG. 12 and FIG. 13 and shows wireends 24 a, 24 b which simply pass over each other to form an enclosedloop or overlap. The discrete radiopaque markers 24 may be plasticallyor elastically deformable. The markers 24 may be springs or spring-likefor attachment purposes. Alternatively, the ends 24 a, 24 b may be tied,knotted, crimped, spot welded, or bent The markers 24 may be relativelysmall and comprise a single loop or pigtail of wire around one filamentcrossing point, filament, an embolization coil, or the like. The marker24 is preferably made of a biocompatible radiopaque material that isductile including pure tantalum, platinum, gold, zirconium, niobium,titanium, stainless steel, or combinations thereof.

The marker 24 may be a pig-tail, coil, or knot design and is preferablyformed from an elongate member such as a wire and shaped accordinglyonto the implantable endoprosthesis 16. The marker 24 advantageouslyallows custom marking of the implantable endoprosthesis 16 without theneed to acquire preformed marker bands or to devise a complicatedmanufacturing operation such as swaging, threading, or braiding. Thediscrete radiopaque markers 24 may be easily and quickly added to theimplantable endoprosthesis 16. Also, only small, specific sites aremarked by the marker 24 so a minimum amount of foreign body materialwould be added to the implantable endoprosthesis 16. The discreteradiopaque markers 24 may be used on an implantable endoprosthesis 16made of a bioabsorbable polymer including polylactide.

The markers 14, 24 should preferably be smaller than the size of theelement in the implantable endoprosthesis 16. The size of the markers14, 24 is also dependent on the type of radiopaque material used. Forexample, tantalum wire (0.006″ diameter, hard drawn) may be used. Thesmaller diameter wire fits through most weaves, is deformable, and maybe cut to size.

Reference is made to FIGS. 12-13 illustrating discrete markers 24 loopedone or more times about a filament or filament crossing point to preventrelease therefrom. The ends 24 a, 24 b are dipped and positioned to liein a plane parallel to the longitudinal axis of the implantableendoprosthesis 16. The marker 24 may be disposed on one or more filamentcrossing or every other filament crossing point around the circumferenceof the braid in one circular transverse plane. The markers 24 may bepositioned to form one or more circumferential rings on the implantableendoprosthesis 16. Alternatively, the markers 24 may be positioned alongan embolization occlusion coil intravascular device or filament atpredetermined locations as illustrated in FIG. 15. The marker 24 may beplastically deformed and the marker ends 24 a, 24 b may be looped one ormore times about a portion of the implantable endoprosthesis 16 and thenpulled to provide a snug disposition. The ends 24 a, 24 b may then betied, twisted, knotted, welded or adhesively connected together andthereafter clipped and positioned to lie in an unobtrusive low-profileposition.

It will be evident from considerations of the foregoing that theretrievable radiopaque marker 14 and discrete radiopaque marker 24 maybe constructed using a number of methods and materials, in a widevariety of sizes and styles for the greater efficiency and convenienceof a user.

A bioabsorbable marker that may advantageously be used in conjunctionwith the present invention is disclosed in J. Stinson's United StatesPatent Application entitled “Bioabsorbable Marker Having RadiopaqueConstituents And Method Of Using Same”, Ser. No. 08/904,951, filedconcurrently herewith, and commonly assigned to the assignee of thisapplication.

A bioabsorbable stent that may advantageously be used in conjunctionwith the present invention is disclosed in J. Stinson's United StatesPatent Application entitled “Bioabsorbable Implantable EndoprosthesisWith Reservoir And Method Of Using Same”, Ser. No. 08/905,806, filedconcurrently herewith, and commonly assigned to the assignee of thisapplication.

Another bioabsorbable stent that may advantageously be used inconjunction with the present invention is disclosed in J. Stinson'sUnited States Patent Application entitled “Bioabsorbable Self-ExpandingStent”, Ser. No. 08/904,467, filed concurrently herewith, and commonlyassigned to the assignee of this application.

The above described embodiments of the invention are merely descriptiveof its principles and are not to be considered limiting. Furthermodifications of the invention herein disclosed will occur to thoseskilled in the respective arts and all such modifications are deemed tobe within the scope of the invention as defined by the following claims.

What is claimed is:
 1. An implantable endoprosthesis and radiopaquemarker system comprising: an implantable endoprosthesis adapted to bedisposed in a body lumen; and at least one elongate marker having aproximal end, a distal end, a thickness, and at least one radiopaqueportion, the radiopaque portion including a radiopaque material whereinthe marker is removably attached to at least a portion of theimplantable endoprosthesis and is at least partially removable from theendoprosthesis by a force when the endoprosthesis is in vivo.
 2. Theimplantable endoprosthesis and radiopaque marker system of claim 1wherein the radiopaque material has a linear attenuation coefficientranging from about 5.46 cm⁻¹ at 50 KeV to 149.08 cm⁻¹ at 50 KeV.
 3. Theimplantable endoprosthesis and radiopaque marker system of claim 1wherein the marker has a thickness of from about 20 microns to about 500microns.
 4. The implantable endoprosthesis and radiopaque marker systemof claim 1 wherein the marker includes a material selected from thegroup consisting of barium sulfate, bismuth trioxide, iodine, iodide,titanium oxide, zirconium oxide, gold, platinum, silver, tantalum,niobium, stainless steel, and combinations thereof.
 5. The implantableendoprosthesis and radiopaque marker system of claim 1 wherein themarker is coated or alloyed with a radiopaque material.
 6. Theimplantable endoprosthesis and radiopaque marker system of claim 1wherein the marker crosses at least one portion of the implantableendoprosthesis.
 7. The implantable endoprosthesis and radiopaque markersystem of claim 1 wherein the marker is in a form selected from thegroup consisting of wire, mono-filament, multi-filament, ribbon, suture,spring, and combinations thereof.
 8. The implantable endoprosthesis andradiopaque marker system of claim 1 wherein the marker comprisesmaterial selected from the group consisting of metal, polymer,copolymer, ceramic, and combinations thereof.
 9. The implantableendoprosthesis and radiopaque marker system of claim 1 wherein themarker includes at least one hollow, cavity, or porous portion.
 10. Theimplantable endoprosthesis and radiopaque marker system of claim 1wherein the marker includes at least one hollow, cavity, or porousportion therein adapted to receive the radiopaque material.
 11. Theimplantable endoprosthesis and radiopaque marker system of claim 1wherein the radiopaque portion is at least one of a liquid, solid,powder, gel, wire, mono-filament, multi-filament, pellet, particle, andcombinations thereof.
 12. A method of marking an implantableendoprosthesis comprising the steps of: removably-attaching at least oneradiopaque means to a portion of an implantable endoprosthesis to forman assembly; disposing the assembly in a delivery system; inserting thedelivery system in a body lumen; deploying the assembly from thedelivery system into the body lumen; and removing at least a portion ofthe at least one radiopaque means from the implantable endoprosthesisusing a force.
 13. An implantable endoprosthesis and radiopaque markersystem comprising: an implantable endoprosthesis adapted to be disposedin a body lumen; and at least one radiopaque means removably attached toat least a portion of the implantable endoprosthesis wherein at least aportion of the at least one radiopaque means is removable from theendoprosthesis by a force when the endoprosthesis is in vivo.
 14. Theimplantable endoprosthesis and radiopaque marker system of claim 1wherein the radiopaque material has a linear attenuation coefficientgreater than 149.08 cm⁻¹ at 50 KeV and less than about 151.53 cm⁻¹ at 50KeV.
 15. The implantable endoprosthesis and radiopaque marker system ofclaim 1 wherein the radiopaque material includes iridium.
 16. Animplantable endoprosthesis and radiopaque marker system comprising: animplantable endoprosthesis adapted to be disposed in a body lumen; andan elongate marker having at least one radiopaque portion including aradiopaque material, wherein the marker is removably attached to theimplantable endoprosthesis and is removable from the endoprosthesis whenthe endoprosthesis is in vivo.
 17. The system of claim 16 wherein: theradiopaque material includes at least one element having an atomicnumber of at least 22 and at most
 83. 18. The system of claim 17wherein: the radiopaque material includes said element in a formselected from the group consisting of: a metal, a metallic alloyincluding the element, an oxide including the element, and a saltincluding the element.
 19. The system of claim 17 wherein: the markerincludes a polymer matrix combined with a powder, and the powderincludes the element.
 20. The system of claim 16 wherein: the radiopaquematerial has a linear attenuation coefficient of at least 5.46 cm⁻¹ at50 KeV.
 21. The system of claim 16 wherein: the radiopaque portion ofthe marker is provided as a coating.
 22. The system of claim 16 wherein:the marker is provided in a form selected from the group consisting of:wires, monofilaments, multifilaments, ribbons, sutures, springs, andcombinations thereof.
 23. The system of claim 16 further including: adelivery device adapted for a delivery of the endoprosthesis to a bodylumen and a withdrawal of the delivery device from the body lumen afteran implantation of the endoprosthesis within the body lumen; and whereinthe marker is attached to the delivery device whereby said withdrawal ofthe delivery device removes the marker from the endoprosthesis.
 24. Thesystem of claim 16 wherein: the marker is woven into the endoprosthesis.25. The system of claim 16 wherein: the marker is formed as a spring,and when so removably attached is retained with respect to theendoprosthesis by a spring force.
 26. The system of claim 16 furtherincluding: an adhesive for temporarily securing the marker to theendoprosthesis.
 27. The system of claim 16 further including: a wire,engaged with the endoprosthesis and with the marker, for removablyattaching the marker to the endoprosthesis.
 28. The system of claim 27wherein: the wire is so engaged in a manner that requires a removal ofthe wire from the endoprosthesis before removal of the marker from theendoprosthesis.
 29. A process for modifying an implantableendoprosthesis to temporarily enhance a visualization of the prosthesisduring and after an implantation thereof in a body lumen, comprising:providing a body implantable endoprosthesis; providing at least onemarker, each marker having at least one radiopaque portion including aradiopaque material incorporating an element with an atomic number of atleast 22; and prior to an implantation of the endoprosthesis, attachingthe at least one marker to the implantable prosthesis in a manner thatfacilitates a removal of the marker from the endoprosthesis when theendoprosthesis is in vivo after an implantation thereof.
 30. The processof claim 29 wherein: the attaching of the at least one marker to theendoprosthesis comprises using a mode of attachment selected from thegroup of modes consisting of: weaving the marker into theendoprosthesis, providing the marker as a spring having a spring forceand using the spring force to retain the marker attached to theendoprosthesis, and applying the marker to the endoprosthesis using anadhesive.
 31. The process of claim 29 further including: after attachingthe at least one marker to the endoprosthesis, mounting theendoprosthesis releasably to a delivery device.
 32. The process of claim31 further including: securing the marker to the delivery device, toenable a removal of the marker from the endoprosthesis by withdrawingthe delivery device from the endoprosthesis after its implantation.